A unit called the hundredweight ought to be the least confusing measure imaginable. It is right there in the name: a hundred of something. Yet the British hundredweight is 112 pounds, the American one is 100 pounds, and the gap between them caused enough commercial friction that laws were passed about it. The hundredweight is a beautiful little case study in how units go wrong.
The unit itself is old, rooted in the medieval practice of trading bulk goods — wool, grain, metal — in large standardized sacks and bundles. A hundredweight was, originally, a hundred pounds, back when it was often called a centum or quintal.
How 100 became 112
The drift came from the convenience of other units. English trade came to favor the stone of 14 pounds, and merchants wanted the hundredweight to contain a whole number of stones. Eight stone made 112 pounds — close enough to a hundred to keep the name, tidy enough to win. The number 112 also divides nicely for quarters: the quarter, at 28 pounds, was a genuine trading unit, and 112 splits into four of them cleanly.
England formalized the 112-pound hundredweight centuries ago, and the imperial ton followed as 20 hundredweight, giving the famous 2,240-pound long ton.
America keeps the honest hundred
American merchants, less attached to the stone, stuck with the literal reading: a hundredweight of exactly 100 pounds, called the cental or short hundredweight, with the 2,000-pound short ton as 20 of them. For a while both hundredweights circulated in Anglo-American trade, and the mismatch was a genuine source of disputes — a cargo priced per hundredweight meant different money depending on whose hundredweight applied. British law eventually regulated which versions could be used in trade, and careful contracts learned to spell out the exact unit.
The two systems remain neatly parallel and stubbornly incompatible:
| Unit | US (short) | UK (long) |
|---|---|---|
| Hundredweight | 100 lb | 112 lb |
| Ton (20 cwt) | 2,000 lb | 2,240 lb |
Where you still meet the cwt
The hundredweight, abbreviated cwt (the c from Latin centum, a hundred), is far from dead. In the United States, agricultural commodities such as cattle, hogs, rice, and milk are commonly priced per hundredweight — market reports quote dollars per cwt daily. In the UK, the hundredweight lingers in older trades and in tradition, though metric units have taken over commerce; a metric successor, the 50-kilogram quintal-style measure, plays a similar role in some countries.
Anyone reading historical documents, farm market reports, or old freight rates will bump into cwt eventually, and the only question that matters is which side of the Atlantic wrote it.
When you see cwt, translate before you calculate: 100 pounds in an American context, 112 in a British one, and roughly 45.4 or 50.8 kilograms respectively.
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